Ketogenesis is a natural catabolic process that takes place in the liver through the breakdown of fatty acids into ketone bodies (KBs). Three different KBs generated in this metabolic process include: i) acetoacetate; ii) β-hydroxy butyrate; and iii) acetone. The generation of ketone bodies is different in a healthy person compared to a hyperglycemic or type-1 diabetic patient (e.g., the breath ketone level of a healthy person and a diabetic patient varies for example within ranges of 0.3-0.9 ppm and >1.8 ppm, respectively). For a type-1 diabetic patient, the pancreas produces an insufficient amount of insulin. A high level of insulin suppresses the rate of ketogenesis and a lower amount of insulin can lead to an increase of ketone bodies in blood, including glucose. No direct relationship has been established yet between ketone and glucose generation, though it is evident that both glucose and KBs are at elevated levels for hyperglycemic patients. The elevated level of KBs turns the blood acidic, which is the most serious hyperglycemic emergency in patients with type 1 diabetes, referred to as “diabetic ketoacidosis” (DKA). Elevated levels of ketone can also be generated due to starvation, exercise, or alcohol consumption; nonetheless, DKA is the most severe case as the ketone levels can more than double. Moreover, it can critically affect the heart, muscles, the respiratory system, the gastrointestinal system, and/or the central nervous system and can result in a coma or death.
The existing methods for measuring ketones include point of care and laboratory blood tests, urine tests by chemical strips, and lung ketone analysis by breath analyzers. In the blood tests, β-hydroxy butyrate is monitored, and in the breath tests acetone is monitored. Blood testing is an invasive test while acetone monitoring from urine and breath are both noninvasive. Unfortunately, these methods do not monitor ketone levels continually and alert the subject if a dangerous state of DKA occurs. It is life threatening if DKA occurs while the patient is asleep.
In addition, existing standalone organic volatile sensors are incapable of specifically detecting a single specific volatile organic compound in a multi-dimensional environment. The non-specific detection of the existing sensors generates false positives and false negatives. It is noted that multi-dimensional environments are common and exist in all biological fluids and vapors.